Built my express and it works, but...

[keithrick]

Don't forget the 47pf cap across the 82K and 100K in the PI. Might help with the sizzle!

[jjman]

If you have a dual trace scope you can check both PI outputs at the same time. One side may be not running. If both PI outs are running ok, and the speaker output is clipping on only one half, I would suspect the preamp is clipping too soon.